Rate dependence of corrosion-induced surface cracking in concrete: lattice modelling and experiments

It is not fully understood how corrosion-induced cracking in reinforced concrete is affected by current density, which controls the corrosion rate in experiments with impressed currents. Here, it is tested if creep is the dominant mechanism by combining experiments with impressed current densities of 50, 100 and 500 μ A/cm 2 and water–cement ratios of 0.38, 0.45, 0.55 and 0.70, and numerical modelling with a random lattice approach which accounts for creep but neglects by design both migration of corrosion products and the dependence of corrosion product composition on corrosion rate. Based on the experimental results, corrosion penetration at a fixed surface crack opening is found to increase with decreasing corrosion rate and with increasing water–cement ratio. The lattice approach incorporating fracture and creep, but excluding migration and compaction of corrosion products, significantly underestimates the experimentally observed dependencies of corrosion-induced cracking on corrosion rate for high water–cement ratios. This demonstrates that fracture and creep alone are insufficient to reproduce the experimentally observed rate dependence of corrosion-induced cracking.